Micro-sized needles, i.e. needles having diameters and lengths in the micrometer range, find great utility i.a. in many medical applications.
Typical fields of application are various electrical measurements performed on the skin, using arrays of micro-needles. For electrical applications it is often desirable to provide individual needles or groups of needles that are electrically insulated from each other in the lateral direction, but where the needles are in electrical contact with the back-side of the substrate on which they are provided.
Other fields of application are for thin film thickness/impedance measurements (e.g. in the IC industry) where micro probe heads are needed. Also for chip probing robust miniaturized needles are required.
Such lateral insulation and vertical electrical “through connection” finds wider applications, and can be used for a plurality of applications where signals needed to be routed from a device through a substrate.
In U.S. Pat. No. 4,356,056 there is discloses a method using under-etching for the provision of mesa structures on a circuit-board.